• Proceedings of the KSME Conference
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• 2000.04b
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• pp.398-403
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• 2000

Experimental study on the porous ceramic burner for oil burning has been performed. Temperature profile of the combustor and CO and NOx emission have been obtained for with and without porous ceramic plate. It is found that very uniform and high temperature region with porous ceramic plate can be realized due to high radiation emission from the plate and also obtained lower CO and soot particulate emission, when compared to the conventional burner. When this burning method is applied to conventional boiler of small heating capacity, it is found that near 6 and 7 percent increase in thermal efficiency could be obtained without a proper calibration for optimization.

• Clean Technology
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• v.23 no.2
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• pp.181-187
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• 2017

The perfluorocompounds (PFCs) emitted from the semiconductor and display manufacture is treated by abatement systems which use various technologies, such as combustion, thermal, plasma, catalyst. However, it is required that the system should overcome their drawbacks with excess energy consumption and low removal efficiency. The new technology using combination of pressure swing adsorption and excess enthalpy combustion for the reduction of PFCs emissions were developed and analyzed its characteristics. PFCs concentration ratio and PFCs loss factor were calculated from measuring concentration of PFCs at the calculated by comparing concentration of PFCs at the combustor's inlet and outlet. There were performance evaluations with various gas flow for comparing energy consumption and removal efficiency with existing equipments. The concentration ratio and the loss factor of PFCs were 1.65, 8.2%, respectively, when the total gas flow of the pressure swing absorption (PSA) inlet was 204 liter per minute (LPM) and $CF_4$ concentration was 1412 ppm. In comparison with existing system at constant condition, $CF_4$ removal efficiency for a porous media combustion (PMC) showed the improvement more than 16% and the consumed energy was also reduced up to approximately 41%. Then, the total gas flow introduced into PMC and $CF_4$ concentration were 91-LPM and 2335 ppm, respectively, and the destruction and removal efficiency of $CF_4$ was about 96% at 19-LPM $CH_4$, and 40-LPM $O_2$.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.676-684
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• 1990

This study is on the pulsating combustion of premixed gas in a Rijke type combustor made of a honeycomb flame holder in a tube. Modelling for the onset condition of the oscillation is made by the ratio of the acoustic power generation based on the analysis of heat transfer to the power loss due to the thermoviscous dissipation and radiation. Experiment is performed for the characteristics of acoustic, thermal and combustion. It is shown that the theoretical modelling for the oscillation may be used as a limit condition. And the combustion analysis for the acoustic power generation is needed for better prediction of the onset condition. Experimental result shows that, by pulsation, the flame length is shortened and the flame temperature is decreased with increase in the heat transfer coefficient. The NO$_{x}$ concentration in the exhaust gas is significantly reduced by pulsation and the concentration of unburned hydrocarbon shows a little increase.e.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.559-567
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• 1995

The combustion process within a porous inert medium (PIM) burner is numerical studied. A detailed chemical reaction scheme including thermal and prompt NO$_{x}$ reactions is used to predict the formation and destruction of pollutants such as NO$_{x}$ and CO. The reaction paths for NO$_{x}$ formation are divided to quantify the amount of NO$_{x}$ formed through thermal NO$_{x}$ reaction or through prompt NO$_{x}$ reaction. Emission index is calculated to compare the actual mass of NO$_{x}$ or CO produced through the combustion of unit mass of fuel. It is found NO formation in PIM burner is confined in flame zone and formation is suppressed due to heat loss at down-stream of the flame. Higher production of NO through prompt NO reaction path is observed due to the higher concentration of fuel derivative species and its higher diffusion at flame front. For all equivalence ratios, CO emission within PIM burner is lower than that from the one-dimensional freely-propagating flame. PIM burner flame has better NO$_{x}$ emission index from .psi. = 0.75 to .psi. = 1.1. to .psi. = 1.1.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.235-243
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• 2001

This paper describes a design study of the cylindrical multi-hole premixed burner to be used for condensing gas boiler which can raise performance and reduce NOx emission. In this study, specifications of the multi-hole burner (hole diameters and arrangement) are investigated using model flat burners in terms of flame stability, and combustion characteristics for stability and NOx emission are examined for cylindrical multi-hole burner. As a result, the equivalence ratio for optimum operation condition of the cylindrical burner is around 0.72(0.7∼0.75). In this condition, turn-down ratio becomes 3 : 1 at least which is suitable for proportional control. The NOx and CO emission is less than 40ppm and 25ppm(0$_2$0% basis), respectively. This burner can be applied LPG as well as NG because there is no difference for stable combustion region.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.162-169
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• 2005

The performance of oxygen combustion with $CO_2$ feeding was investigated in a pyrex tube furnace. The inverse type multi-hole burner was used for improving mixing and wide operating range. It introduced oxygen, fuel, and oxygen, respectively, from center tube to outer tubes. Oxygen combustion characteristics with excess oxygen ratio, oxygen feeding ratio, and $CO_2$ feeding flow rate were studied to optimize the operating condition and to apply the oxygen combustion with recirculation of flue gas to a real furnace. This paper presents results on the effect of $CO_2$ feeding flow rate on the structure of the flames and concentrations of NO and CO emissions. The visible flame length was shortest due to well mixing between fuel and oxygen when the oxygen feeding ratio was 0.25. The NO emission was reduced drastically regardless of excess oxygen ratio when the $CO_2$ feeding flow rate was larger than 15 lpm. The CO emission is varied by changing the $CO_2$ feeding flow rate but the CO emission characteristics is highly affected by excess oxygen ratio. When the excess oxygen ratio is below ${\lamda}=1.1$, the CO emission increased as the $CO_2$ feeding flow rate increased.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.151-154
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• 2011

$NO_x$ 제어 기술로는 크게 연소 전 탈질, 연소 개선 및 연소 후 탈질 기술로 구분할 수 있으며, 연소 후 탈질 기술에 속하는 SCR은 촉매를 사용하여 $NO_x$를 환원하는 대표적인 배연탈질기술이다. SCR의 $NO_x$ 저감 성능은 촉매 요인(촉매 구성물질, 형태, 공간속도 등)과 배가스의 온도, 유속 분포, 공정 운전 조건 등의 다양한 인자에 의해 좌우되는데 특히, 촉매층으로 유입되는 유동의 균일도는 가장 중요한 요소가 된다. 유동이 균일하지 않을 경우 촉매 전단에 편류가 발생하게 될 것이며 일정 촉매만 사용하게 되어 촉매 사용주기 감소 및 SCR 성능 저하를 초래할 수 있기 때문이다. 본 연구에서는 3차원 수치 해석 기법을 이용하여 설계 초기의 SCR 반응기 내 유동 특성을 모사하여 기류 균일도 여부를 확인하고, SCR 내 유동 균일도를 최적화시키기 위한 설계를 목적으로 설치하는 가이드 베인과 배플, 다공판이 반응기 내부 유동 및 촉매층의 기류 균일도에 미치는 영향에 대하여 연구를 수행하였다. 그 결과, 유동 개선을 위해 인입 덕트 곡관부에 가이드 베인을 설치하여 처리가스를 적절하게 배분시키고, 반응기 상단에 3단 배플을 설치한 결과 반응기 내부 유동의 편류 개선에 매우 효과적임을 알 수 있었다. 또한 다공판을 예비 촉매층 하단부 위치에 추가로 설치함에 따라 유동을 한번 더 완충시킬 수 있어 기류 균일도가 매우 양호해짐을 알 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.9
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• pp.623-629
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• 2017

Flow structure and mixing characteristics in a micro combustor with a multi-hole baffle were numerically studied using the Reynolds stress model. The multi-hole baffle has geometrical features to produce multiple three-dimensional vortices inside combustion chamber. When the thickness of the baffle's geometrical factors changes, variations of vortical structures occur variously. Among these vortices, the vortex generated from the fuel stream exerts a critical influence on the mixing enhancement. The three-dimensional vortical structure, in its development state, was strongly dependent on the baffle thickness. In particular, as the baffle thickness decreases to values less than the diameter of the fuel hole, the jet stream in baffle holes changes from the parabolic to saddleback profile type. The sizes of recirculation zones inside combustion chamber and the mixing state were closely affected by the structure of the jet streams.

• Journal of the Korean Society of Combustion
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• v.4 no.1
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• pp.95-103
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• 1999

Experimental study on combustion characteristics of a regenerative combustor has performed. High-temperature air combustion in the regenerative combustor is obtained through heat recovery from exhaust gas flow by porous ceramic materials and through alternation of air flow direction through the combustor. Temperature field, CO and NOx emission with respect to the frequency of alternation are measured. It is found that at initial stage of the alternation, temperature of inlet section of main combustion chamber is increased sharply since both high temperature air preheated by the ceramics and prompt fuel injection results in rapid combustion. Following this initial stage, combustion temperature is reduced as the preheated air temperature is reduced. However peak temperature in the chamber and exhaust gas temperature are decreased as the alternation period is reduced, increased temperature of ceramic is observed. CO and NOx emission with respect to the alternation period is also examined. It is found that there exists a range of optimum alternating period for CO and NOx emission characteristics.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.4
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• pp.17-23
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• 2007

This paper describes the flow and performance characteristics inside the post-chamber of the multi-port hybrid rocket motor. Using the computational fluid dynamics (CFD) technique, the non reactive compressible flow fields in the downstream of the fuel grain was numerically calculated. The motor performance obtained from computational results were in agreement with that conducted by the ground motor firing test. Besides, the flow field characteristics inside the post-chamber were discussed under different port numbers (1 port and 3 ports) of the fuel grain. The flow pattern showed that the performance of multi-port hybrid rocket motor having three grain ports is higher than that of the single-port one due mainly to the difference of incoming mass flow rate irrespective to the pressure field.